General Information:

• Aim: to examine the characteristics and temporal variability of the Antarctic and Arctic ozone holes.
• Websites: 
• http://jwocky.gsfc.nasa.gov/multi/multi.html
• http://jwocky.gsfc.nasa.gov/eptoms/ep.html
• Contents: provides animated images of annual changes in atmospheric ozone levels and user-defined options to view images for specific days.

• The first website provide access to satellite-derived images (from the Earth Probe satellite) and graphs of Antarctic and Arctic ozone levels. 
• Beneath the red title "Antarctic Ozone Hole" are the following resources:
• animated movies (QuickTime, MPEG or GIF format) of the Antarctic ozone hole for 1994, 1996, 1997 and 1998. 
• the color-coded images of the 1996 and 1997 animations depict ozone levels in Dobson units that range as follows:
• deep purple (extremely low levels, ~100) through violet (~200), blue (~250), green (~350), yellow (~400), orange (~450) to red (high levels, ~500). 
• black areas represent regions with no data, either because the satellite did not fly over that region, or because the absence of light precluded measurements.
• a different scale is used for 1994; there is no scale for 1998.
• links to graphs depicting:
• the change in the size (areal extent) of the ozone hole ( http://jwocky.gsfc.nasa.gov/multi/oz_hole_area.gif ) 
• the minimum value of the ozone hole ( http://jwocky.gsfc.nasa.gov/multi/min_ozone.gif ). 
• a composite image of the size of the Antarctic ozone hole in October from 1979 to 1997 is shown at:
• (http://jwocky.gsfc.nasa.gov/multi/monoct.gif ).
• Beneath the red title "North Hemisphere Ozone" there is:
• an animated movie of the development of the Arctic ozone hole in the Spring of 1997 (QuickTime or GIF format), using the same color coding as Antarctica above.
• The second website provides user-defined access to satellite-derived images (from the Earth Probe satellite) of global, Antarctic and Arctic ozone levels for 1996-1998. 
• Four fields can be specified:
• day, month, year, product type (data and images)
• the request button presents the requested data or image 
• product type refers to the area or data required
• the third and fourth selections namely:
• North Pole Ozone - GIF
• South pole ozone - GIF
• Data for the polar views are only available for 6 months of the year (July - Dec. for the S. hemisphere; Jan. - June for the N. hemisphere.) 
• color-coded images depict ozone levels in Dobson units using a scale that differs from the one above.  It ranges from grey (extremely low levels, ~100) through purple (~200), blue (~250), yellow(~350), green (~400), ochre (~450) to red (high levels, ~500). 
• white or black areas represent regions with no data, either because the satellite did not fly over that region, or because the absence of light precluded measurements.
• Suggestion: you can compare ozone levels in the Antarctic and Arctic for specific dates to help answer Questions 1 and 6. 
• obtain individual images of ozone levels for particular days around your target date by entering the day, month and year required, selecting "North Pole Ozone - GIF" or "South Pole Ozone - GIF", and then request.

• The questions are outlined in two tables ( next page , following page)
• they explore temporal changes in the size and shape of the ozone hole over Antarctica and the developing hole over the Arctic.
• Reminder: you should submit your answers via  oncourse .

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